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Pelican Technical Article:

Brake Rotor Replacement


3 hours3 hrs






Phillips head socket tool, rubber mallet, socket set, micrometer

Applicable Models:

Porsche 986 Boxster (1997-04)
Porsche 986 Boxster S (2000-04)
Porsche 987 Boxster (2005-12)
Porsche 987 Boxster S (2005-12)

Parts Required:

Brake discs, new pads, new emergency brake shoes (if required)

Hot Tip:

Adjust your emergency brake while you have access

Performance Gain:

Better, safer braking

Complementary Modification:

Replace brake pads, emergency brake shoes, install stainless steel brake lines, install new wheel bearings
101 Performance Projects for Your Porsche Boxster

This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your Porsche Boxster. The book contains 312 pages of full color projects detailing everything from performance mods to changing your brake pads. With more than 950+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any Boxster owner's collection. The book is currently available and in stock now. See The Official Book Website for more details.

Brake discs (or rotors as they are often called) are a very important part of the braking system. The brake pads rub against the discs to create a friction force that is responsible for slowing the car down. If the rotors become too thin, or develop grooves in them, then their ability to stop the car decreases.

When replacing your brake pads, you should always measure the thickness of your brake discs. If they fall below the specified value for your car, then they should be replaced with new ones. Check for grooves in the rotor, and make sure that you take several measurements of the disc in several different places. This will guarantee you that you get an accurate reading. If the brake disc has a groove in it, then it should most certainly be removed and resurfaced by a machine shop, or simply replaced with a new one. Discs with grooves not only brake less efficiently, but they also heat up to higher temperatures, and reduce your overall braking ability.

The measurements that you take with your micrometer should be made from the center of the disc. It is common for OEM rotors to have the minimum thickness stamped on the rotor hub (as is the case with the ceramic PCCB brake option). If you can't find this information, use the following chart to determine if your rotors need to be replaced.

Type and Year.

Min Thickness.


Front Vented Steel Rotor (Boxster 1997-2004).



Rear Vented Steel Rotor (Boxster 1997-2004).



Front Vented Steel Rotor (Boxster/Cayman 2005-).



Rear Vented Steel Rotor (Boxster/Cayman 2005-).



If you do find that you need to replace your rotors, the process is a relatively simple one. The procedure for the front or the rear rotors is very similar, but for the sake of this project, we'll look at replacing the rears, which is slightly more complicated due to the addition of the rear parking/emergency brake. With the rear rotors, if the parking brake shoes are very worn, then you may need to back off the adjustment sprocket in order to be able to remove the rear disc (see Project 51 for more details).

The first step is to jack up the car and remove the road wheel. If you haven't already, remove the brake pads from the caliper. Refer to Project 49 on replacing brake pads for more details. The flexible rubber brake hose is attached to the trailing arm of the car via a large clip. This clip retains both the flexible line and the hard line that connects to the rear caliper. Remove this clip so that you will be able to remove the caliper without bending the hard metal brake line.

Now, unbolt the caliper from the trailing arm where it is mounted. There should be two bolts that mount the caliper and hold it in place. After you remove these two bolts, you should be able to slightly move the caliper out of the way of the disc. Exercise caution when moving the caliper around - make sure that you do not let the caliper hang from the rubber brake line, as this will most certainly damage the line.

Once you have the caliper out of the way, remove the small screw that holds on the brake disc. You will need a Phillips head socket tool for this task (you can try using a big screwdriver, but odds are the screw will be on too tight, and you may end up stripping it). At this point, make sure that the parking brake is off. You should now be able to pull the disc off of the hub. If there is any resistance, use a rubber mallet to tap the brake disc off. Sometimes the disc will require some heavy smacks with your rubber mallet to get it off.

If you are having a difficult time getting the disc off, it's probably because the parking brake shoes are stuck on the back of the disc. You might need to adjust the parking brake so that it's not gripping the disc. For more information on this process, see Pelican Technical Article: Parking Brake Adjustment.

Installation of the new brake disc is a snap, simply push it onto the hub. Before you install the new disc, take a close look at your parking brake shoes and see if they warrant replacing. If you can see metal on the shoes, or the previous owner had a hard time remembering to remove the emergency brake, then it might be a good time to replace these. After you install the new discs on both sides, you should test your parking brake and adjust it if necessary. Refer to Project 53 and Project 51 for more details.

After the new disc is installed, replace the retaining screw, reattach the caliper, and install new brake pads. Your new rotors should last a long time, and you should see an improvement in your braking after the wear-in period for your new brake pads.

The front and rear brake discs look almost identical.
Figure 1

The front and rear brake discs look almost identical. The rear brake discs have an inner 'drum' area that acts as the surface for the emergency brake to press against. While the Boxster and Cayman both have disc brakes at all wheels, the rear parking brake mechanism is most similar to a drum brake system. You may want to paint the inner hats and edges of the discs with some high-temp paint. This will keep them from rusting after you install them.

Before you remove your brake discs, it is important to first measure them to see if they need to be replaced.
Figure 2

Before you remove your brake discs, it is important to first measure them to see if they need to be replaced. Use a micrometer to perform the measurement. If you use a dial caliper, then you might get a false reading because the disc wears on the area where the pads make contact, not on the edges of the disc. Make sure that you take several measurements in a few different places on the disc in order to compensate for potential low or high spots.

Removal of the caliper is accomplished by unbolting the two hex bolts that mount it to the arm (yellow arrow).
Figure 3

Removal of the caliper is accomplished by unbolting the two hex bolts that mount it to the arm (yellow arrow). The caliper (green arrow) can be pushed out of the away, and doesn't need to be physically disconnected from the brake line. Hang the caliper from a string or coat hanger (blue arrows) so that you don't put unnecessary tension on the rubber brake line (orange arrow).

There are two small locator screws that hold the brake disc in place.
Figure 4

There are two small locator screws that hold the brake disc in place. Use a big screwdriver or a Phillips head socket tool to remove this screw, and the brake disc should slide off of the hub. Keep in mind that the lug nuts that hold on the wheel apply the majority of the force that constrains the disc to the hub: not this screw.

The new disc can be tapped on with a rubber mallet.
Figure 5

The new disc can be tapped on with a rubber mallet. If installing the rear discs, make sure that you have your parking brake shoes adjusted away from the inside drum, or they might interfere with the installation of the disc. New discs may not be perfectly flat, and may take a few hundred miles of break-in to achieve their maximum braking efficiency.

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Comments and Suggestions:
Dragos Comments: Great article guys !
Now for my dilemma: I have a 2008 Boxster, base model and am trying to change the brake discs on the front. I got the Bosch Quietcast online part numbers 42011132 and 42011136, they are supposed to fit, but I believe they are a bit too thick for my car: 319 mm. Do you happen to know the maximum thickness the caliper can take ?

Thanks !
February 27, 2016
  Followup from the Pelican Staff: I don't know that spec, not sure it exists. Give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
Stephen Comments: Do you have the minimum rotor thickness for a 981 2014 Cayman S, both front and rear?
January 27, 2016
  Followup from the Pelican Staff:
I don’t have that info.

We don't currently have that tech article. If we get a chance to perform the procedure, we will be sure to document it.

I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
Luza986 Comments: boxster calipers on boxster s rotors, Would this work?boxster 986
July 2, 2015
  Followup from the Pelican Staff: No. They are different part numbers.- Nick at Pelican Parts  
Piaggio Comments: I have a 2004 986 boxster base. Do you know if the rotor from a 2004 boxster S model will fit?
July 2, 2015
  Followup from the Pelican Staff: No, the part numbers are different. - Nick at Pelican Parts  
cajundaddy Comments: Need to confirm minimum rotor thickness F/R for 987.2 Boxster/Cayman. I believe it is different between base and "S" models but this is not spelled out anywhere. I have a 2009 base Cayman and fronts are good at 27mm. Rears??? I cannot clearly read the stamp on the rotor but I think it says 18mm. Mine currently measure 19.2mm. Anyone know for sure?
April 25, 2015
  Followup from the Pelican Staff: What year and model is your vehicle. With the specific vehicle info, I can see if I have the brake data you are looking for. - Nick at Pelican Parts  
PeterB Comments: I have a 2000 Porsche Boxster. Front cross drilled Zimmermans on the way from you guys. Talking to friends on the track, I'm being cautioned about the Caliper bolts being seized when I loosen them and to be gentle to avoid breaking the bolt which is a real problem to fix if that happens. So when I put the bolts back on, what is the proper torque so I don't over tighten them?
April 19, 2015
  Followup from the Pelican Staff: Caliper to wheel carrier 85 Nm, the bolts have to be replaced each time they are removed. - Nick at Pelican Parts  
Pablo Comments: The head of the bolt see picture broke off when I was tightening it I was unsure of the Torque.
I need you help identifying the bolt. And if you have, any advice in removing the part that’s stuck inside.

January 25, 2015
  Followup from the Pelican Staff: What vehicle are you working on? What article is that image from? For a faster response for the part: Give our parts specialists a call at 1-888-280-7799 and they can help figure out which part or repair kit you need.
- Nick at Pelican Parts
M Comments: I read that the caliper bolts should be replaced every time the rotors are changed. Is this necessary?
August 7, 2014
  Followup from the Pelican Staff: If you read that in Porsche factory information, then do it. - Nick at Pelican Parts  
imaninja Comments: Are all four rotor discs identical or is is specific to front/back and direction of rotation please?
July 7, 2014
  Followup from the Pelican Staff: See this helpful info from dazedandcofused: Hi imaninja, If they are drilled and/or slotted, then the front brakes are unidirectional meaning left and right hand specific. The rear brakes are bi-directional if drilled, doesn't matter which goes where. You would want to install directional brakes so that the hole pattern or slots go in the direction of the wheel rolling forward. Hope this helps : - Nick at Pelican Parts  
Maximus Comments: Do anyone know the size of the two hex bolts on the calipper? I need to by the correct size before i start the operation!
November 2, 2013
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799. They can help you find the right part.
- Nick at Pelican Parts
Mr. Steve Comments: Project is for base Boxster, what are Min. Thickness front and rear for 2003 Boxster S
October 10, 2013
  Followup from the Pelican Staff: The front rotor minimum is 26.0 mm. The rear rotor minimum is 22.0 mm. - Nick at Pelican Parts  
wsp8 Comments: How about putting a thin coating of anti-seize between wheel hub and rotor? The Zimmerman installation guidelines included with the new rotors says 'no', but what's the issue?
September 10, 2013
  Followup from the Pelican Staff: Zimmerman rotors are coated and do not require it. Personally, I have neevr used anti-sieze in between the rotors and the hubs, and I live in a salt belt area. My rule of thumb is if the factory doesn't put it there, I don't. - Nick at Pelican Parts  
Z. Clark Comments: Great write-up! These directions are correct, *2* screws are required per rotor.

The product description here is lying:
May 16, 2013
  Followup from the Pelican Staff: Thanks for the feedback. We'll make the changes to the product description. - Nick at Pelican Parts  
JonasAndersson Comments: Hi, It would be great of all the tourqe values was presented in the different projects.
March 28, 2013
  Followup from the Pelican Staff: Thanks for the feedback. - Nick at Pelican Parts  
Smallblock454 Comments: Sensors only need to be replaced if warning lights came on. Because then the warning sensor is activated/dameged.
March 5, 2013
  Followup from the Pelican Staff: The sensors activate when the rotor comes in contact with the internal wire at the end of the sensor. It is good practice to replace the sensors when pads are replaced. If after an inspection of the sensor and it's mounting no damage is found you could reuse them.

- Denny at Pelican Parts
Bryan Comments: Can anyone tell me if the break wear sensors need to be replaced every time the pads are replaced? And are they on every wheel or just right front and left rear like my wife's E-90 328i? Vehicle in question is a 2006 Boxster. Pad warning came on at 28,000 miles? Any advice on turning or purchasing new discs?
July 30, 2012
  Followup from the Pelican Staff: I suggest replacing the rotors, not machining. There are four brake pad wear sensors, one on each corner. You will have to replace any sensor that is worn. - Nick at Pelican Parts  
Walt Comments: I'm installing OEM rotors. Is there any special preparation or cleaning required on the friction surface?
May 5, 2012
  Followup from the Pelican Staff: Nope, they should just be cleaned off with a paper towel, and make sure you don't accidentally spill any motor oil or brake fluid on them. - Wayne at Pelican Parts  
D Comments: I thought I saw a comment that there was an article on how to paint the calipers, but now I can't find it. Can you point me to the page if there is one.

Thanks, Dave
September 9, 2011
  Followup from the Pelican Staff: I've got an article on this right here: - Wayne at Pelican Parts  

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